This invention relates to the improvement of a mattress for use in, for example, a bed.
A conventional mattress for use in a bed, as shown in FIG. 1, is comprised of a spring assembly 13 constructed by flat-connecting a plurality of coil springs to each other by helical wires 12, a pair of elastic material sheets 15, 16 formed of, for example, polyurethane foam and attached respectively to the upper and lower faces of the spring assembly 13 through a hessian cloth 14, a side-elastic material member 17 encompassing the outer side periphery of the spring assembly 13, and a covering 18 for covering an elastic body consisting of the spring assembly, the elastic material sheet, and the side-elastic material member. The side-elastic material member 17 is provided for the purpose of reinforcing the side periphery of the spring assembly 13 and preventing the spring assembly 13 from being subject to rocking motion. Further, the side-elastic material member 17 is formed at the side face of the spring assembly 13 by subjecting a foamable plastic to foaming-in-place. Therefore, in order that said foamable plastic is prevented from entering the spring assembly 13, a barrier sheet 19 is stretched at the side face of the spring assembly 13.
On the other hand, there is a mattress wherein the elastic material sheets 15, 16 are so extended as to sandwich the side-elastic material member 17 from above and below, as shown in FIG. 2. In such a mattress, the interiors of the extended portions 20, 21 of the elastic material sheets 15, 16 are impregnated with the foamable plastic in the course of its foaming-in-place by which to form the side-elastic material member 17, and therefore are made stiff and intensified.
In any one of the above-mentioned mattresses, however, there is a great difference in modulus of elasticity between coil springs 11 constituting the spring assembly 13 and the side-elastic material member 17, which results in a drawback of giving a user a feeling of physical disorder. In the mattress shown in FIG. 2 such drawback is indeed lessened as compared with the mattress shown in FIG. 1, but not to a sufficient extent.
In the mattress shown in FIGS. 1 and 2, the covering 18 is constituted by upper and lower lining coverings for covering the surfaces of the paired elastic material sheets and a gusset covering for the outer side periphery of the side-elastic material member, and upper and lower edge portions of this gusset covering and respective peripheral edge portions of said upper and lower lining coverings are sewn up together at two portions -- the upper and lower corner portions of the elastic body. The fact that the covering has two sewing-up sections as described above is not preferable from the standpoint of mattress productivity.
Further, sewing-up of the covering is performed usually by a sewing machine, but, in the conventional mattress, portions being sewn up are displaced from each other, so that the resulting sewn-up section becomes disorderly or irregular, that is, has no good appearance. Further, in order to perform the sewing-up of the covering so as to prevent displacement of said portions being sewn up, an expert was required.
This invention has been achieved in view of the above-mentioned circumstances, and an object of the invention is to provide a mattress eliminating a user's feeling of physical disorder as resulting from the difference in elasticity modulus between the side-elastic material member and the coil spring, and capable of reliably preventing a mattress body from being subject to rocking motion.
Another object of the invention is to provide a mattress whose productivity can be raised by providing singly the sewing-up section of the covering and wherein a sewing line of the sewing-up section can be made regular so as to prevent the finished mattress in appearance from having distorted or deformed portions thus to increase the commodity value of the mattress.
Still another object of the invention is to provide a mattress wherein, when a plurality of cloths constituting the covering are sewn up together by a sewing machine, they can with precision and ease be so done at a prescribed position.
The objects of the invention have been achieved through the following characterizing features of the invention.
That is, a first characterizing feature of the invention resides in the respect wherein a mattress of the invention comprises a flat-constructed spring assembly, a pair of elastic material sheets which are attached respectively to upper and lower faces of said spring assembly and whose peripheral edge portions are so extended as to form a space at a side peripheral portion of said spring assembly and are opposed to each other at their respective tip ends, a side-elastic material member formed in said space by subjecting a foamable plastic to foaming-in-place, and a covering means for covering an elastic body consisting of said spring assembly, said elastic material sheets and said side-elastic material member, whereby the respective peripheral edge portions of said elastic material sheets are particularly longitudinally intensified by impregnating said foamable plastic into the whole portions of said respective peripheral edge portions which contact said side-elastic material member.
A second characterizing feature of the invention resides in the respect wherein the mattress is provided with a flange whose inner peripheral portion is embedded in the side-elastic material member and whose outer peripheral portion is drawn outside from the outer side face of the side-elastic material member; and said covering means consists of upper and lower covering sheets which cover upper and lower halves of said elastic body, respectively, and whose peripheral edge portions are sewn up together at the central portion of the side face of said elastic body.
A third characterizing feature of the invention resides in the respect wherein, in the mattress having said flange, to a peripheral edge portion of at least one of said covering sheets being sewn up a guide member functioning as a guide when said peripheral edge portion of said one covering sheet is sewn up together with a peripheral edge portion of the other covering sheet is attached.